Assembling your units for March on the Drina

About March on the Drina, from BoardGameGeek:

"March on the Drina" is a 2-4 player wargame, set in World War I historical period, which covers the Balkan peninsula theater. Austria-Hungary, Germany and Bulgaria are invading Kingdom of Serbia. The goal of the game for Central powers is to occupy all cities in Serbia, while Serbia`s goal is to prevent that and liberate all of its territory. Each side has four types of units: infantry, cavalry, artillery and generals. The map is divided in hexagons and only one unit can occupy one hexagon. National military capacity is gained by controlling the cities and it is used to reinforce your armies. Each general has special abilities which are forwarded to the troops under his control. The game lasts 14 rounds max where each round represents one period of 1914-1918 conflict and that period is described on one card of the Calendar and it brings special effects on one round of the game. -description from the designer